Tools for setting blind rivets



Dec. 10, 1968 R. M. ELLIOTT TOOLS FOR SETTING BLIND RIVETS Filed Sept. 23, 1966 Inventor R/e/mra M Elliott by lu's /itfarvzey United States Patent 3,415,102 TOOLS FOR SETTING BLIND RIVETS Richard M. Elliott, Beverly, Mass., assignor to United Shoe Machinery Corporation, Boston, Mass., :1 corporation of New Jersey Filed Sept. 23, 1966, Ser. No. 581,482 5 Claims. (Cl. 72-391) The present invention relates to improvements in tools for setting blind rivets of the type set by pulling upon a frangible mandrel which breaks and is disposed of after the rivet has been set. More particularly the invention relates to improvements in the loading of rivets in such tools and to the disposal of spent mandrels. Hereinafter all reference to rivet setting tools is intended to apply to all types of tools which are adapted to performing a blind riveting operation or setting a rivet while operating from one side of a work piece only and in which the rivet setting is accomplished by a pull exerted upon .a frangible mandrel which breaks and must be disposed of after the setting of the rivet.

Such rivet setting tools whether hand or power operated are limited in the maximum achievable operating rate by the time required to load the rivet in the tool preparatory to setting and the time necessary for the disposal of the mandrel after the rivet has been set. Accordingly numerous partially successful attempts have been made to mechanize these two aspects of the total rivet setting operation. In conventional tools attempts to solve these problems have usually considered the two problems separately. For example, tools have been connected to central mandrel collectors by means of flexible hoses through which the broken mandrels were impelled by a high vacuum source. Such a solution, however, is only partially successful because of the frequency of jams occurring inside the hose particularly at bends and the limitation on tool maneuverability imposed by the relative rigidity of the hose which must be tough and thick walled to resist both internal and external abrasion. A related difficulty is that the internal hose diameter must be several times the diameter of the mandrel in order to permit the mandrel to negotiate its passage through bends in the hose. This tends to require not only a more rigid hose because of its larger diameter but also to necessitate a high order of vacuum and accordingly costly pumps for itsimplementation.

Attempts which have been made to automate the loading of rivets in setting tools have generally taken either of two forms: tool mounted magazines or delivery of individual rivets to the tool from a central reservoir through a flexible hose. The mounting of a magazine on the tool, together with associated mechanisms required for conveying rivets from the magazine to operative position in the tool, tends to add substantially to the weight of the tool and, in addition, often renders it impossible to use the tool in cramped surroundings.

The main object to an arrangement for delivering rivets individually through a hose to the riveting tool is that the addition of the hose interferes with the maneuverability of the tool. It is readily appreciated that in an air operated tool, for example, which is powered through a high pressure air line connected to the tool, that the addition of a second hose, through which rivets are delivered to the tool, and a third hose for removal of the spent mandrels to a disposal unit, would render the tool so difficult to maneuver as to add substantially to operator fatigue and accordingly further reduce normal production. In addition, tools which are equipped with hoses through which the rivets travel to the tool also require some form of rivet positioning device mounted near the nosepiece of the tool and these also tend to interfere with the setting of rivets in close quarters.

3,415,102 Patented Dec. 10, 1;)68

It is accordingly an object of the present invention to provide cooperatively associated means for loading blind Emits into riveting tools and for disposing of spent manre s. Another object of the invention is to assist in the loadmg of rivets into riveting tools without at the same time substantially impairing maneuverability of the tool.

Yet another object is to provide for the automatic disposal of spent mandrels from riveting tools without requiring expensive .accessory equipment and without incurring time delaying blockages or jams in the disposal apparatus.

A further object of the invention is to improve the effective operating speed of riveting tools by reducing the time required for loading of rivets into the tool and the disposal of spent mandrels while retaining the ability of the tool to perform a riveting operation in cramped quarters.

In the achievement of the foregoing objects one of the features of the invention relates to a spent mandrel receiving canister or receptacle of convenient size mounted directly upon the riveting tool and connected to a vacuum source. Because the canister is mounted a short distance from the operative parts of the tool, it is possible to convey broken mandrels to the canister through a straight tube of relatively small diameter and as a result the mandrel may be propelled through the tube with a low vacuum on the order of about 2 lbs. per square inch below atmosphere. Such vacuum may be produced by inexpensive low capacity pumps.

Another feature of the invention relates to a mug formed with an interior cavity for receiving rivets in position to be picked up by the riveting tool. The mug is completely separate from the riveting tool and may conveniently be connected to a central rivet reservoir by means of a flexible hose through which the rivets are delivered one at a time to the cavity. The mug and above mentioned canister cooperate with each other since the vacuum source which propels the spent mandrels into the canister is also effective for lifting a1 rivet from the mug cavity into the nose piece of the riveting tool when the tool is brought into loading relationship with the mug.

According to a related feature of the invention, sensing means is provided on the mug for initiating the delivery of a rivet to the mug from the reservoir in response to the presentation of the riveting tool to the mug to load the tool with the rivet already in the mug cavity. As a result of this feature a continuous supply of individual rivets delivered to the mug is assured without any special attention being given on the part of the operator so that his entire attention may be concentrated on the riveting operation.

The foregoing objects and features and numerous advantages to be derived from the invention will be best understood from the following detailed description of an illustrative embodiment takenin connection with the accompanying drawings in which:

FIG. 1 is a view in prespective showing a riveting tool and mug according to the present invention;

FIG. 2 is a fragmentary view in longitudinal section of the mug and the operative end of the tool of FIG. 1 in which the tool is depicted in rivet receiving position;

FIG. 3 is a fragmentary view in cross section showing a cover for a canister of the tool also forming a part of the showing of FIG. 1;

FIG. 4 is a fragmentary view in cross section and on an enlarged scale taken along the line IV-IV of FIG. 2 and illustrating the position of a spent mandrel as it moves through a passage in the riveting tool; and

FIG. 5 is a fragmentary view in cross section showing the operative end or nose of the tool depicted in FIGS. 1 and 2 with a rivet in operative position.

Turning now to the drawings, especially FIGS. 1 and 2, there is shown a powered riveting tool comprising a housing on which is mounted a canister or receptacle assembly indicated generally at 12 in which spent mandrels are collected. Cooperating with the riveting tool is a mug indicated generally at 14 formed with an internal cavity 16 to receive individual rivets 18.

Although the illustrative tool is designed for power operation such as by means of an electric motor or pneumatic or hydraulic cylinder, the basic principles of the present invention are equally applicable to manually operated tools. The illustrative tool includes, as seen particularly in FIG. 2, a draw bar 20 to the lower end of which is afiixed a jaw operating cage 22 containing a pair of mandrel gripping jaws 24. The lower end of the tool terminates in a nose piece 26 formed with a central passage or guideway 28 adapted to locate the rivet 18 in operative position to be gripped by the jaws 24. The rivet 18 consists of a rivet body 30 and a rivet setting mandrel 32. A loose sliding fit is provided for the mandrel in the guideway 28 of the nose piece. There is located above the jaws 24 a spring pressed plunger 34 formed with a wedge shaped head 35 which urges the jaws 24 apart when the draw bar 20 is in its lowermost position. As the draw bar 20 is raised the head 35 of the plunger 34 under the urging of a spring 36 presses the jaws 24 downwardly into the cage 22. As the jaws move downwardly they securely grip the mandrel 32. The draw bar 20, which is formed with an interior passage 38 continues to move upwardly and in so doing deforms the rivet 30 and finally causes breakage of the mandrel 32. In power operated tools provision is made for the return of the draw bar 20 to the position of FIG. 2.

In general that part of the tool which has thus far been described may be considered as conventional and as mere background for the invention. Specific problems to which the present invention is addressed are those of facilitating loading of the tool preparatory to a rivet setting operation and of disposal of the mandrel at the completion of the operation. Both objectives are realized by the use of vacuum on the order of 2 or 3 p.s.i. below atmospheric pressure and provided by a low capacity pump communicating with the tool through a lightweight flexible hose 40 connected to the interior of the receptacle assembly 12 through a cover 42. The body 44 of the receptacle is advantageously fabricated of a clear plastic tube and a seal is provided between the body 44 and the cover 42 by an O-ring 46 as seen in FIG. 3. A straight rigid pipe 48 rigidly connected to the draw bar 20 extends into the canister 12 and thus places the passage 28 in the nose piece in communication with the vacuum provided by the hose 40 through the passage 38 in the draw bar and a passage 50 in the plunger 34. When a mandrel breaks at the end of a rivet setting operation and the draw bar 20 and the jaws 24 are returned to the position depicted in FIG. 2, the mandrel is released and is impelled through the passages 28 and 50, 38 and the pipe 40 into the receptacle 12. The passages 28, 50, 38 and the interior of the pipe 48 are in alignment so that they provide the necessary guidance for the mandrel 32 and avoid jams by confining the spent mandrel relatively closely as it progresses from the nose piece to the receptacle 44. A typical example is that a steel mandrel .062 in diameter and approximately 1 /2 inches long is readily impelled through passages 50, 38 and the interior of the pipe 48 under a pressure differential of approximately 2 p.s.i. when these passages are approximately .088 inch in diameter. Obviously, adjustment would have to be made either in pressure differential or in the size of the passages to accommodate mandrels of substantially different diameters or weight.

The mug 14 comprises a body 52 in which the cavity 16 is formed. At the top of the cavity 16 there is a funnel shaped surface 54 adapted to receive and centralize the nose piece 26 by fitting a conical portion 56 on the housing 10. The funnel surface 54 is formed with a shallow trough 58 in line with the discharge of a flexible hose 60 through which rivets are delivered one at a time to the cavity 16. The hose 60 is secured to the body 52 by a clamp 62 and there is also mounted with the clamp on the mug body 14, a normally closed switch 64 actuated by a spring pressed plunger 66. An integral flange 68 on the plunger 66 is engaged by a compressed spring 70 between the flange and a threaded plug 72 for urging the plunger inwardly. When the tool is inserted into the mug to pick up a rivet, the plunger 66, the upper end of which projects inwardly of the surface 56, is depressed from the dash line position to the solid line position of FIG. 2 and opens the switch 64. Through a wire 74 the switch 64 is connected in series with a control device such as a relay or a solenoid of a remotely located rivet feeder member, not shown and not forming a part of the invention per se. Closure of the switch initiates delivery of a rivet propelled by a blast of compressed air through the hose 60 to the cavity 16 to replace the one which has just been picked up by the tool. Each rivet 18 is oriented to travel body first through the hose 60 and successive rivets fall uniformly into position in the cavity 16 as shown in FIG. 2.

Alternative means are provided for centralizing the mandrel 32 of the rivet so that it readily enters the guideway 28. The rivet assembly shown in the drawings is one in which the rivet flange is formed with a conical surface 76, FIG. 4. With a rivet so constructed, the nose piece 26 is formed adjacent the guideway 28 with a concave conical mating surface 77 which funnels the mandrel 32 into the guideway as the rivet assembly is lifted from the cavity 16 by the air pressure differential. The concave surface which is intended to fit the flange of the rivet during setting thus provides a convenient means for centralizing the mandrel 32 for entry into the guideway 28 of the nose piece. However, other rivets to be loaded from the mug 14 may have other than conical flanges which accordingly do not lend themselves to the convenient approach since it is preferred that the rivet engaging surfaces of the nose piece conform to the flange.

The alternative device for centralizing the mandrel 32 is accordingly provided in the mug to be used in conjunction with flat ended nose pieces, for example. The alternative centralizing means comprises a pair of plungers 78 and 80 each urged outwardly by a light spring 82. The plungers 78 and 80 are slidable in counterbored cylindrical guideways for-med in the mug and each is retained against excess travel in the guideway by a plate 84 secured to the outer surface of the mug. The springs 82 exert a minimal outwardly directed force on the plungers 78 and 80 so that the force is readily overcome and the plungers move inwardly to embrace the mandrel 32 under the partial vacuum resulting in the cavity 16 when the nose of the tool is inserted into the mug 14. As the nose piece 26 is raised from the mug 14, the pressure in the cavity is raised and the plungers 78 and 80 are pressed radially outwardly by the springs 80. Appropriate camming surfaces 85 on the plungers 78 and 80 are engageable by the body 30 to assist in retracting the plungers for passage of the rivet assembly 18 into the nose piece 26. For faster and more positive centralizing action but at a cost of greater weight of the mug 14, a solenoid may also be provided on the mug for actuating the plungers 78 and 80.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination with a tool having a hollow nose piece and a pair of rivet setting jaws for setting a rivet including a rivet body and a frangible mandrel to which a tractile force is applied for setting the rivet body in a work piece and then breaking the mandrel after the rivet body has been set, means defining a spent mandrel collecting canister mounted on the tool, a vacuum source connected to the canister and means defining a relatively straight passage interconnecting the nose piece with the canister and adapted to guide spent mandrels from the nose piece to the canister.

2. A tool according to claim 1 further characterized in that the passage is of a diameter less than twice that of the mandrel whereby a source of low vacuum may be employed for propelling spent mandrels through the passage to the canister.

3. The tool according to claim 1 further comprising means for centralizing the mandrels of rivets to be aspirated into the nose piece.

4. The tool according to claim 1 in combination with a mug formed with an integral cavity and means for centralizing a rivet in the cavity and means for aligning 15 5 at a time in position to be loaded into the setting tool from the cavity.

References Cited UNITED STATES PATENTS 3/1963 Bosch 72--391 3,196,662 7/1965 Simmons 72-391 CHARLES W. LANHAM, Primary Examiner.

G. P. CROSBY, Assistant Examiner. 

1. IN COMBINATION WITH A TOOL HAVING A HOLLOW NOSE PIECE AND A PAIR OF RIVET SETTING JAWS FOR SETTING A RIVET INCLUDING A RIVET BODY AND A FRANGIBLE MANDREL TO WHICH A TRACTILE FORCE IS APPLIED FOR SETTING THE RIVET BODY IN A WORK PIECE AND THEN BREAKING THE MANDREL AFTER THE RIVET BODY HAS BEEN SET, MEAN DEFINING A SPENT MANDREL COLLECTING CANISTER MOUNTED ON THE TOOL, A VACUUM SOURCE CONNECTED TO THE CANISTER AND MEANS DEFINING A RELATIVELY STRAIGHT PASSAGE INTERCONNECTING THE NOSE PIECE WITH THE CANISTER AND ADAPTED TO GUIDE SPENT MANDRELS FROM THE NOSE PIECE TO THE CANISTER. 